Building a Mast Mount

2017-09-22 at 01:42

Once I had a strategy for the mast display hardware it was time to figure out how I was going to actually secure it on the boat. The mounting position on the boat is pretty unique because of the tapered mast shape and the fact that it needs to be offset a couple inches to provide clearance for the lines coming down the mast.

My first task to was take a profile of the mast shape. My dad was in the middle of assembling a new spar so I was able to simply trace around the base of it to capture the profile, and then I recorded caliper measurements of both his and my spars.

Ultra precise mast section profile measurements

My friend (and crew!) had been telling me a lot about 3d printing. I thought it might be a good way to prototype the mount. After much analyses paralyses I landed on a Wanhao Duplicator i3 plus clone from MicroCenter. I immediately set out to improve print quality using parts designed by the community and printed on the machine itself.

New toy

It took me a couple weeks, but I finally learned enough freecad, fusion 360, and Cura to get me to the point where I could start to be productive.

Several nights were spent in this format after the kids went to bed. Designing a part, watching a part print, coding on gibbs.

My first real print was to duplicate the mast section to use as a test rig. I did this with PLA since it wouldn't ever see any real wear.

Printing the test mast section

My friend told me about a newer filament by m3d called "tough ink" which yields flexible, durable parts. Perfect for my application. I created a "test strap" which I could use on my spar to get an idea how it should fit.

The test strap

Testing the fit I found that I was going to need a little more offset than I anticipated to make it fit around the cunningham.

The test strap In Situ

The next fit I needed to perform was for the inkBook itself. This part was pretty easy since I could just take caliper measurements and enter them directly to my fusion 360 sketch. I did a quick PLA print just to verify the fit and then stopped it about 1/2 through when I was satisfied.

Test fitting the inkbook

Finally, 2 days before our national regatta I kicked off a blue tough-ink print of the completed mount, it was slated to take ~30 hours to print. Unfortunately at about 4 am that night the print head clogged and I woke up to the machine "printing air". I had to scramble a bit to modify the settings so that I could print a new mount in time for my departure, so I lowered the infill and speed things up. Thankfully this print went off without a hitch and I had my completed mount for the regatta.

The entire lineup, with the finished prototype on the right

My current model can be seen in fusion 360 here. The final result turned out reasonably well I think considering the short timetable in which it was designed and made. Tough ink is somewhat hard to "clean up" after a print so it's not the smoothest looking fixture around but it is very durable. The question of waterproofing remains on my mind. There are a few options that range from simple (just shrinkwrap the inkbook) to more complex (print a slot for a sheet of acrylic and silicone it in place), I'm not sure what I'll do yet.